topic Re: AGV network and AGV process flow in FlexSim Forum

AGV network and AGV process flow

tzu_hsuan_c — Fri, 11 Jun 2021 16:33:11 GMT

[ FlexSim 21.1.3 ]

hi, recently I'm learning AGV module. I have some confused problems.

1. There several types of control point connections, control point tell AGV it's destination. So one control point can connect to above one different control points depending on how many destination it can go to? For example, following CP A can connect to both CP B and CP C?

2. My understanding is some CPs are used for defining a location, some are for AGV making decision. Such as the CP B in above picture is for Look for Work, CP A is a location that represents Queue4? When connect one CP to next CP, what's the difference in NextLookForWork and LookForWork?

3. I know in FlexSim, there are built-in AGV process flow that can be used directly. But after I complete 3D model and connections, do I have to set in anything to let AGV follow those logic to execute tasks? What is the built-in rule for excecuting tasks (pull from list), is it FIFO? And if I'd like to use custom dispatching rules, simply revise from the original Process flow(without build a logic from beginning)? And the places that I need to revise is to by determine when to let push to list happen, also set in list reference?

Attached is my model, but it still can not transfer on path at the moment. One station.fsm I'm really lack of concept in AGV module. Thank you for your patience and assistance in advance!

Re: AGV network and AGV process flow

eric_m3 — Fri, 11 Jun 2021 20:47:24 GMT

Hi @Tzu Hsuan C, there were only a couple small things incorrect in your model, so you are on the right track. First, the AGVs needed to be connected to the process flow. This is done by clicking on a blank part of the flow and selecting the AGVs in the properties window:

Then the source needs to send the item somewhere. I did this with an a-connection, but you could use any of the normal output options. The use transport box needs to be selected. Here you change it to use list and select the AGVWork list. This list is used in the process flow and is needed when sending items. The last thing to correct on your model was the location control points. Those should be connected to the main work loop (red arrows). I changed them to come from the control point that is pointing to the drop off connection as shown below. one-station.fsm

1. If you haven't already, I would go through the AGV tutorial or watch the AGV template video here (either all or just the basic). The template in its most basic form has the AGVs travel around the next look for work loop (red arrows) to find tasks to complete. At each control point, the AGV checks if there's an item to load or unload and then moves to the next point. All the other connection types add a little more control over how the AGV travels / makes decisions (like where to pick up or unload). So CP A can connect to B and C although you want to make sure the next look for work (red) go in a loop (if CP A was connected to B it would have nowhere to go next and stop).

2. LookForWork allows the AGV to look at multiple places for work when it comes to a CP. With the basic NextLookForWork the AGV will only check if there's work at a CP when it gets to that CP. With LookForWork, the AGV can look ahead to make decisions on where it should go next (look under the LookForWork Fowarding section in process flow for more explanation or here).

3. You just need to connect the AGVs to the flow to get it to work and make sure the use transportation is set to push it to the AGVWork list. The work is organized based on what CP the AGV is at. Yes, you can adjust the template, so you don't need to start from scratch. The goal of the template is to give you something that works that you can also modify as needed.

Re: AGV network and AGV process flow

tzu_hsuan_c — Sat, 12 Jun 2021 09:09:56 GMT

If using LookForWork, but there are too much items in system. Will AGVs still follow every CP sequences to check if there's task, rather than skip to the last CP before Sink?

In my model, item creation is faster than producing cycle time. I find AGVs blocked, maybe this won't happen if I use NextLookForWork. But I think blocked also should not happen using LookForWork.

Three stations.fsm

Re: AGV network and AGV process flow

eric_m3 — Mon, 14 Jun 2021 14:39:20 GMT

Yes, using LookForWork, the AGVs will follow the sequence and check for work at each point. TaskExecuter2 is being blocked because it has to wait for TaskExecuter1 to finish loading / unloading etc. It doesn't have much to do with the type of path being used rather than TE2 not being able to allocate the next CP because TE1 is already allocating it. One way to fix this would be to have TE2 start halfway around the loop, That way it's not right behind TE1 the whole time. Adding more intermediate CPs might help as well so the TE can allocate the next CP more easily.